1. Field of the Invention
A combined sensor and control for maintaining constant flow of hydraulic working fluid under varying loads.
2. Prior Art
In many types of equipment employing hydraulic power mechanisms which are subjected to varying loads, the hydraulic mechanism is connected in a circuit so as to be driven by a pump which, in turn, is driven by a prime mover. Often, in a given operating cycle, the load imposed on the mechanism varies from very light to extremely heavy. If the input of the prime mover to cause it to operate at a given speed for a light load is maintained constant, the prime mover cannot operate at the same speed for a heavier load. On the other hand, if the input is maintained constant for a heavy load the prime mover will operate at a very high speed if the load is reduced, thus creating undue noise, wastage of fuel, and subjection of the driven mechanism to severe inertial forces.
To overcome these and other disadvantages, various types of controls have been devised for changing the input to the prime mover in response to the hydraulic pressure demands imposed by the load. Most frequently the prime mover is an internal combustion engine of the gasoline operated type and the input is the fuel supply to the engine. This supply is controlled by a conventional throttle which generally is spring closed and which can be opened to varying degrees manually or by various types of throttle actuating devices so as more nearly to balance the output of the engine with the instant load being imposed by the hydraulic mechanism being operated.